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The role of protonation in protein fibrillation
Author(s) -
Jeppesen Martin D.,
Westh Peter,
Otzen Daniel E.
Publication year - 2010
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/j.febslet.2010.01.002
Subject(s) - isothermal titration calorimetry , protonation , fibrillation , chemistry , titration , population , lysozyme , peptide , charge exchange , glucagon , side chain , biophysics , biochemistry , hormone , inorganic chemistry , ion , medicine , biology , organic chemistry , polymer , demography , sociology , atrial fibrillation
Many proteins fibrillate at low pH despite a high population of charged side chains. Therefore exchange of protons between the fibrillating peptide and its surroundings may play an important role in fibrillation. Here, we use isothermal titration calorimetry to measure exchange of protons between buffer and the peptide hormone glucagon during fibrillation. Glucagon absorbs or releases protons to an extent which allows it to attain a net charge of zero in the fibrillar state, both at acidic and basic pH. Similar results are obtained for lysozyme. This suggests that side chain p K a values change dramatically in the fibrillar state.